Before taking doxazosin,
tell your doctor and pharmacist if you are allergic to doxazosin, prazosin (Minipress), terazosin, any other medications, or any ingredients in doxazosin tablets or extended-release tablets. Ask your pharmacist for a list of the ingredients..
tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Be sure to mention any of the following: antihistamines; clarithromycin (Biaxin, in Prevpac); ipratropium (Atrovent, in Combivent); itraconazole (Onmel, Sporanox); ketoconazole (Nizoral); medications for erectile dysfunction (ED) such as sildenafil (Revatio, Viagra), tadalafil (Adcirca, Cialis), or vardenafil (Levitra, Staxyn); medications for high blood pressure; medications for HIV/AIDS including atazanavir (Reyataz), indinavir (Crixivan), nelfinavir (Viracept), ritonavir (Norvir, in Kaletra), or saquinavir (Invirase); medications for irritable bowel disease, motion sickness, Parkinson's disease, ulcers, or urinary problems; nefazodone; telithromycin (Ketek); and voriconazole (Vfend). Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
tell your doctor if you have angina (chest pain); low blood pressure; if you have ever had low blood pressure after taking a medication; or if you have or have ever had prostate cancer, or liver disease. If you are taking the extended-release tablet, tell you doctor if you have constipation, short bowel syndrome (a condition where more than half of the small intestine has been removed by surgery or damaged by disease), or narrowing or a blockage of the intestines.
tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking doxazosin, call your doctor.
talk to your doctor about the risks and benefits of taking doxazosin if you are 65 years of age or older. Older adults should not usually take doxazosin because it is not as safe as other medications that can be used to treat the same conditions.
if you are having surgery, including dental surgery, tell the doctor or dentist that you are taking doxazosin. If you need to have eye surgery at any time during or after your treatment, be sure to tell your doctor that you are taking or have taken doxazosin.
you should know that doxazosin may make you drowsy or dizzy. Do not drive a car, operate machinery, or perform dangerous tasks for 24 hours after the first time you take doxazosin or after your dose is increased.
you should know that doxazosin may cause dizziness, lightheadedness, and fainting when you get up too quickly from a lying position. This is more common when you first start taking doxazosin, when your dose is increased, or if your treatment has been stopped for more than a few days. To avoid this problem, get out of bed slowly, resting your feet on the floor for a few minutes before standing up. If you experience these symptoms, sit or lie down. If these symptoms do not improve, call your doctor.